N.C. means Normally closed
N.O means normally opened...
its like norally is when there is no power to it.. in the case of some switches its like with noral pressure and the valve is normally closed.. and when you get too much pressure it opens... and then closes when the pressure goes down.....
in the case of the Wide open trottle the thing is normally closed and opens when you gun it so the engine can give all its power to the drivetrain so you can drive off like a bat out of hell... with the a/c compressor engaged you will suffer some loss of power due to the compressor using up some of the power.......
